FHWA Memorandum to Virginia DOT, "I-81 Public-Private Transportation Act Proposals" (May 6, 2003), available at: http://www.fhwa.dot.gov/programadmin/contracts/ppta.htm.

FHWA Memorandum to Colorado DOT, "NEPA for Toll Roads" (Oct. 15, 2004), available at: http://www.environment.fhwa.dot.gov/guidebook/NEPA_tollroads.asp.

FHWA, "Program Guidance on Linking the Transportation Planning and NEPA Processes" (Feb 23, 2003), available at: http://www.fhwa.dot.gov/HEP/plannepa.htm.

FHWA, "Fact Sheet: SAFETEA-LU Tolling Programs" (undated), available at: http://www.fhwa.dot.gov/safetealu/factsheets/tolling.htm.

FHWA, "Tolling and Pricing Opportunities" web site (undated), available at: http://www.ops.fhwa.dot.gov/tolling_pricing/.